Proper construction of residential and commercial buildings requires that the building be as level as possible. In many instances, the ground on which the building is constructed is not level. Monetary concerns, engineering factors or other circumstances may make it impractical to engage earth moving equipment to level out the lot on which the building is to stand. In such circumstances, the building is usually built upon a network of piers and beams which provide a level foundation for the remainder of the structure. The use of height adjusting piers is especially prevalent in the "set-up" of mobile and modular residential and commercial buildings.
Height adjusting piers are often constructed of tiers of concrete masonry blocks laid in a "basketweave" pattern. The first tier of blocks is laid with the next tier perpendicular or 90.degree. offset from the first tier. The tiers continue this alternating pattern until the desired height is reached. Typically, the upper tiers are not secured by mortar as the pier is built because final adjustments to the height of the pier may be necessary.
The use of piers as support structures creates the potential for future problems and this potential must be addressed during construction. Simply stated, a column with constant cross-sectional area loses stability against torsional loading as it gets higher. For example, as the height of a pier increases, it loses its ability to withstand toppling under a direct wind applied against the side of the building it supports. Over time wind, settling of the structure and ground and other factors can loosen the blocks in the pier thereby creating the potential for catastrophic failure of the building's foundation.
Accordingly, almost all states and counties have building codes that govern the use of piers in residential and commercial buildings, and particularly with regard to the set-up of mobile homes and modular buildings. For example, the State of North Carolina requires a professional engineer to certify the set-up of a mobile or modular building if over twenty-five percent (25%) of the piers are in excess of thirty-six (36) inches in height. Typically, the set-up of these "over-high" mobile home and modular buildings requires some type of reinforcement of the piers. The most common method of reinforcing piers for mobile homes and modular buildings is to plaster the piers with a material known in the trade as "surwall". Surwall is a dry, powdered concrete product that has fiberglass reinforcement mixed in with the powder. Surwall is mixed with water and applied over the outer surfaces of the pier. Once the surwall dries, the blocks in the pier are secured into position from the plastering effect of the surwall.
Using surwall as a means for reinforcing piers is undesirable for several reasons. For example, using surwall can be a time consuming undertaking. Two hours is often required to reinforce a single pier that is seventy-two (72) inches high. In addition, the mixing, spreading and clean-up of surwall poses the same difficulties as concrete. Both men and material are tied up cleaning equipment after the surwall is applied. Surwall also prevents reuse of the blocks. If the building is to be moved, as mobile and modular buildings often are, the pier must be removed. The surwall ensures that the blocks in the pier must be broken apart which usually damages the blocks.
Another known method for stabilizing a structure formed of multiple stacked blocks is discussed in U.S. Pat. No. 5,444,952 to Jackson ("Jackson"). Jackson discusses stabilizing a brick chimney by placing angle iron at each of the four corners of a chimney, wrapping cables around the chimney and angle iron then tightening the cables.
The Jackson apparatus and method are inadequate in that they rely upon cables which are susceptible to stretching or cutting. Further, although the Jackson apparatus provides external compression to help stabilize the chimney, the Jackson apparatus lacks interior cross members to help stabilize the structure against torsional loadings. Thus, a chimney incorporating the Jackson apparatus remains susceptible to failure under torsional loadings.
Accordingly, a need exists for an apparatus and method for quickly and efficiently securing and stabilizing buildings incorporating piers formed of stacked blocks. This apparatus and method should be compatible with traditional methods of block pier construction and should allow the re-use of blocks if the mobile home or modular building is relocated.